Switch device



March 12, 1946. L. D. BoYcE SWITCH DEVICE Original Filed June 15, 1940 sa 5r fum/im- `54 INVENTOR LEONARD D. BOYCE ATTORNEY Patented Mar. 12, 1946 2,396,551 SWITCH DEVICE Leonard D. Boyce, Maplewood, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Original application June 15, 1940, Serial No. 340,819. Divided and this application February 12, 1941, Serial No. 378,651

(Cl. 20G- 59) Claims.

This invention relates to transmission control mechanisms for automotive engines and consists particularly in novel means for preventing operation of the so-called over-drive throw-out when the vehicle is travelling at such a rate of speed that the consequent increased speed oi the engine would endanger the parts thereof.

This application is a division of my co-pendiligoapplication, Serial No. 340,819, filed June l5,

Where the transmission gearing for an automobile is provided with a so-called over-drive, which is engaged automatically when the vehicle is travelling at higher than a predetermined speed, it is desirable to provide for greater power and faster acceleration particularly in case of an emergency as when the vehicle, though travelling in over-drive, must suddenly be speeded to pass another car. This result is now attained in some instances by automatically reshifting to a higher or more powerful gear ratio when the throttle pedal is fully depressed. It has been found that with such arrangements, where the vehicle is travelling at 45 miles an hour or faster, the transmission cannot be safely returned to third gear, as above described, due to the consequent excessive engine speed.

Accordingly, it is an object of the present invention to provide means for preventing reshifting of the transmission gearing to third gear from over-drive when the car is travelling at faster than a predetermined rate of speed, say 45 miles an hour.

A more detailed object is to provide in the circuit for controlling an over-drive throw-out solenoid, a switch which is jointly controlled by the carburetor throttle valve and a device actuated by greater than a predetermined degree of suction in the carburetor mixture conduit anterior to the throttle. This suction device is sensitive to operation of the engine at approximately the speed where it is undesirable to throw-out the overdrive, to render the throttle control ineffective to close the switch. These objects and other more detailed objects hereafter appearing are attained substantially by the structure illustrated in the accompanying drawing in which:

Fig. 1 is a diagrammatic view showing portions of an automobile engine including the carburetor and transmission with the invention applied thereto.

Fig. 2 is an enlarged view of a portion of the carburetor shown in Fig. 1 but taken at 90 thereto, the over-drive throw-out switch being sectioned on line 2 2 of Fig. l for clearer illustration.

Fig. 3 is a sectional view of the switch as in Fig. 2 but showing the switch contacts engaged.

Fig. 4 is a view similar to Fig. 3 but showing the switch contacts rendered ineffective to complete the over-drive throw-out circuit.

Fig. l shows at Il) a portion of an internal combustion engine of the automotive type including an intake manifold II mounting a carburetor generally indicated at I2. LA clutch and change speed transmission gearing of any suitable form are mounted, respectively, in housings I3 and I4 secured to the rear` portion of the engine. The transmission is pro-vided with over-drive mecha nism located within a housing I5 forming a rearward extension on housing I4 and directly connected to the usual propeller shaft i6 for driving the rear aXle. A soleno-id device Il is mounted on the sideV of the over-drive housing I5, and, when energized, functions in a known manner to throw-out the over-drive or, in other words, return the transmission gearing from over-drive position to third or the next higher `and more powerful gear ratio.

Solenoid I'I is controlled by an electrical circuit including storage battery I8 having one terminal grounded, as at I9, and a switch device generally indicated at 2Q mounted upon the carburetor I2. The storage battery and switch are connected to solenoid I'I, respectively, by leads 2I and 22, the latter being connected to an insulated terminal 23 forming one of the contacts of switch 20 (Figs. 2, 3 and 4) The detailed construction of the solenoid as well as the over-drive and other parts of the transmission do not in themselves, constitute the present invention and are not illustrated. For convenience I have shown a manual shift lever 24 for shifting the transmission gearing through the usual reverse, and first, second and third forward gears, but this shifting may be effected by other suitable means. Asis well known, the over-drive portion of the transmission is automatically engaged responsive to predetermined output speed of the transmission mechanism or, in other words, wheel speed.

Heretofore, the control circuit for the overdrive throw-out solenoid I'I has been controlled solely by e, throttle actuated switch so that whenever the throttle pedal 25 is fully depressed, this solenoid is energized for automatically reshifting from over-drive to third gear. In the present invention I incorporate an additional suction control for the solenoid switch which renders the switch ineiiective to energize the solenoid under predetermined suction conditions. This switch includes an angular body portion 3d, the legs thereof being hollowed as at 3| and 32. Hollow leg 3l forms a cylinder for slidably receiving a cup-shaped piston 33 normally urged downwardly by a coiled spring 3d seated against an inner surface of the piston and a shoulder 35 formed in the upper portion of the cylinder. A passage 36 connects the cylinder above piston 33 to the interior of the carburetor barrel or mixture conduit preferably at the throat of venturi 3l (Fig. 2). A port 3s connects the cylinder below the piston to atmosphere and this port may lead to the air inlet horn of the carburetor so that the air will be drawn through the usual air cleaner (not shown). Secured to the undersurface of piston 33 is an angular spring clip 3l', the projecting leg of which carries a metallic ball or enlargement 33 adjacent, but normally slightly spaced from the inner extremity of switch contact 23 (Fig. 2). The body 5 of the switch device is grounded through the carburetor, intake manifold, and engine block, but piston 33 is formed of insulating material to prevent snorting of switch Contact 23.

The other hollowed arm of the switch body slidably receives a hollowed switch actuating plunger 40 and a collar 4l formed on a pin d2 slidably received within plunger Il@ and extending longitudinally through a screw cap G3 secured to the end of this leg of the switch body. Collar 4l is normally urged outwardly against cap 43 by a coiled spring 44 and plunger lil is similarly urged outwardly by a coiled spring 45 whereby a yielding one-way connection is formed between the switch plunger and pin d'2. One of the primary features of the instant invention is the relationship between the spring tit and the spring 45. The spring d has a compressive strength of approximately one pound to three pounds greater than the compressive strength of the spring 45. This results in a one to three pound limitation on the pressure which may be applied to the Contact points 3S. These contact points are frequently made of silver and would be deformed by the excessive pressure which might be exerted by the pressure of the drivers root on the accelerator. The spring arrangement is such as to resist in ward movement of the control member 40 after the throttle has been opened to a predetermined position so as to contact the switch points and compact spring 135. Thereafter, a conscious effort of the operator will be required to compress spring 44 and telescope rod d2 into member 4t.

Pivotally mounted in the carburetor mixture conduit posterior to venturi 3l' is a buttery throttle valve t which may be manually operated in the usual manner by means of a suitable arm 52 (not shown) rigidly attached to throttle shaft 5i. Also formed on throttle arm 52 is an extension 53 positioned to engage stop iii to nx the wide open position of the throttle valve, and a second arm 55 carrying an adjustable screw 56, the end 56 of which engages the stop 5d to ix the closed position of the throttle valve. A third arm 5l formed rigidly with throttle crank 52 is positioned to engage switch contact pin l2 when the throttle valve is substantially Vfully opened (Figs. 3 and 4) to urge this pin and switch contacting plunger 4t inwardly against enlargement 38 carried by piston 33 and to urge this enlargement in the direction of switch contact 23. Spring 3d is adjusted so as to maintain piston 33 in its lowermost position, as in Fig. 3, whenever the suctio-n at the throat of venturi 31 is less than approximately 1.8 inches of mercury, which corresponds with a vehicle speed of approximately 45 miles an hour. When this degree of suction is exceeded at the throat of the carburetor venturi, that is, when the vehicle is travelling in excess of 45 miles an hour, piston 33 Will be lifted against spring 311 into engagement With shoulder 5B form-ed in the wall of cylinder 3| so as to raise enlargement or ball 38 and prevent contact of switch terminal 23 thereby (Fig. 4). Thus, when the predetermined venturi suction is exceeded, the switch is automatically rendered ineffective to energize the overdrive throw-out solenoid il. tion in venturi 3l is less than approximately 1.8 inches of mercury, ball 3% will be positioned so that when plunger 40 is forced inwardly due to the throttle valve being fully opened, switch contact 23 will be grounded through this enlargement, plunger 4i) and the switch body so as to complete the solenoid control circuit and cause reshifting of the transmission mechanism from over-drive to third gear.

By means of the illustrated structure, the overdrive, which is automatically engaged at a wheel speed of, say 35 miles an hour, may be thrown out whenever the driver demands maximum power and fully opens the throttle valve, but at vehicle speeds in excess of 45 miles an hour, when it would be unsafe to reshift the gearing from over-drive to a higher ratio of engine to wheel speed, such reshiftng is automatically prevented. Thus, it is possible to use a higher third gear ratio than heretofore so as to attain better power and acceleration at the lower speeds.

The invention may be modied in various respects as will occur to those skilled in the art and the exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

I claim:

1. In a switch device for use in connection with an internal combustion engine intake conduit, a body having a chamber and means to transmit suction in the intake conduit thereto, an element movable in said chamber responsive to Varying suction conditions therein, an electrical terminal member in the wall of said chamber, a switch control member extending into said chamber and spaced from said terminal member, and a flexible projection on said suction responsive element adapted to be interposed between said members under predetermined suction conditions in said chamber so as to render said control member, when actuated, operative to complete an electrical circuit passing in part through said `terminal member and said projection.

2. In a switch device for use in connection with an internal combustion engine intake conduit, a body having a chamber and means to transmit suction in said conduit thereto, an element movable in said chamber responsive to varying suction conditions therein, an electrical terminal member in the wall of said chamber, a switch control member extending into said chamber and spaced from said terminal member, and a resilient projection on said suction responsive element normally spaced from said terminal member regardless of the position of said element, said projection including electrical conducting means and being adapted to be interposed between said members under predetermined suction conditions in said chamber so as to be moved against said terminal member upon actuation or" said control member to complete an electrical circuit passing Whenever the sucin part through said terminal member and said projection.

3. In a switch device for use in connection with an internal combustion engine intake conduit, a body having a chamber and means to transmit suction in said conduit thereto, an element movable in said chamber responsive to varying suction conditions therein, an electrical terminal connection in the Wall of said chamber, a movable electrical contact device extending into said chamber and constantly spaced from said terminal connection, and a flexible projection on said suction responsive element including electrical conducting means normally spaced from said terminal connection regardless of the position of said suction responsive element, said projection being adapted to be interposed between said connection and said contact device under predetermined suction conditions in said champosition to a second position; said second conductor when in its said iirst position being flexed to electrically connect said rst and third conductors in response to movement of said third conductor to its second position; said second conductor when in its said second position being disposed out of electrically connecting relationship with said first and third conductors; means actuated by said throttle adjusting mechanism for moving said third conductor; and means responsive to pressure variation in said intake system for moving said second conductor to its said second position.

5. In a device of the class described, a carburetor having a conduit, a throttle valve in said conduit, an operating member for said valve, a relatively stationary electrical conductor, a movable electrical conductor element adapted to be disposed in contactable relationship with respect to said xed conductor, a plunger element adapted for movement by said valve operating member for moving said movable conductor element in contact with said stationary conductor, mechanism for moving said plunger element as aforesaid in response to operation of said valve operating member, means providing a ground for one 0f said elements, and a spring opposed suction device responsive to predetermined suction in said conduit at a point anterior to said valve for moving said movable conductor element to a position thereof out of said contactable relationship.

LEONARD D. BOYCE. 

